Roller rock bit



June 29, 1954 a BAKER 2,682,389

ROLLER ROCK BIT Filed July 20, 1949 2 h ets-Sheet 1 June 29, 1954 vk w"m. 4

Patented June 29 1954 ROLLER ROCK BIT Buford M. Baker, Garland, Tex.,assignor to Engineering Laboratories, Incorporated, Tulsa, Okla., acorporation of Oklahoma Application July 20, 1949, Serial No. 105,838

2 Claims.

This invention relates to roller rock bits for use in the drilling ofoil wells and the like and particularly to the arrangement of such bitswith respect to the flow of flushing fluid therethrough.

It has long been common practice to drill oil wells and the like byrotating 2. string of drill pipe with a roller cone cutter rock bitattached to its lower end, and to circulate mud downward through thedrill string, outward through the bit and upward around the outside ofthe drill string. Such roller cone cutter rock bits usually have threecones, but sometimes have only two and may have more than three. Thepurpose of this mud circulation is mainly to bring cuttings dislodged bythe drill bit to the surface of the earth. It also has the effect offlushing cuttings from between the teeth of the roller cone cutters and,to a certain extent, lubricating the operation of the drill bit.

Originally, it was considered sufiicient to simply discharge the mudfrom the shank of the drill bit at a point above the roller cutters. Forthis purpose a simple axial opening was provided through the drill bitshank. More recently, however, attempts have been made to control theflow of mud at the point of its discharge to accomplish a more effectivecleaning of the spaces between the drill bit teeth. Thus for example, inUnited States Patent No. 2,104,823 to Sherman, the shank of the drillbit is shaped to divide the mud stream into separate jets, one for eachcutter, and each jet is directed radially inward toward one of the conecutters.

It has now been found that prior constructions are inefficient for tworeasons. First, they do not keep the bottom of the hole free fromcuttings, although they do effectively wash cuttings out of the wellonce the cuttings get up into the main mud stream. Secondly, these priorconstructions do not effectively remove cuttings from between the teethof the roller cone cutters.

In prior bits it has been found that cuttings will accumulate beneaththe bit and that the teeth of the bit will wear against these cuttingswithout making appreciable progress in the cutting of the bottom of thehole. As a result, only very finely ground cuttings arrive at the top ofthe hole, although the mud stream would obviously carry much largercuttings and the cutters of the bit would obviously cut much largercuttings. Furthermore, when the bit is withdrawn from the hole thespaces between the teeth of the cutters are often packed with cuttings.

Accordingly, it is the purpose of the present invention to assure athorough flushing, at all times, of the very bottom of the hole, and atthe same time, to assure a thorough cleaning of the spaces between thedrill bit teeth by the jetting of the incoming mud tangentially alongthe faces of the roller cone cutters, from base to apex, where it willbe most efiective to remove cuttings from between the teeth.

The change in the bit necessary to effect the improvements of thisinvention is entirely to the shank or body portion of the bit. In athree cone bit, which is typical of the bits generally used today,although two and four cone bits are sometimes used, the shank or bodyportion of the bit terminates at its lower end in three downwardlydepending legs, upon each of which is mounted a roller cone cutter, andthere is a hole through the center of this shank through which mud isforced downwardly against the upper surfaces of the cutters. A part ofthis mud passes downwardly between the cutters to the bottom of the wellbut the major proportion passes outward into the well between theadjacent cutter cones and the lower edge of the shank between thedownwardly depending legs thereof. In prior constructions there has beena considerable area left open for the escape of mud at the three pointsjust under the edges of the shank and between the downwardly extendinglegs thereof.

Obviously, these three openings can not be completely closed, but it hasbeen found that by making the lower edge of the shank, between thedownwardly extending legs, fit closely to the teeth of the cones,without any more clearance than is necessary to assure free rotation,the escape of mud through these three openings can be greatly reducedand the major portion of the mud caused to circulate completely to thebottom of the well, thus rapidly removing cuttings from under the teethof the cutters.

It has also been found that by so forming the shank, the mud passageterminates in definite and properly positioned jets, the spaces betweenthe teeth can be cleaned much more efiiciently and a much greaterproportion of the mud stream directed against the bottom of the well.

Thus, in a three-cone bit, it has been found expedient to form aseparate jet for each of the three cutter cones and to arrange each ofthese jets so that it projects mud along the face of the cone from thebase towards the apex. It has also been found expedient to provide anadditional jet, in the center of the shank, directed axially downward sothat fiuid from this jet will pass directly downward over the points ofthe cones and onto the bottom of the well.

Further details and advantages of this invention will be apparent fromthe appended drawings and the following detailed description thereof.

In the drawings:

Figure 1 is a side elevation of a well drill;

Figure 2 is a bottom plan view of a well drill having one cutting conemounted to the body portion thereof;

Figure 3 is a view in vertical section of a well drill bit constructedin accordance with the principles of the present invention, two of thecutter cones being removed for convenience of illustration; and

Figure 4 is a view in section taken along line 44 of Figure 3.

Now referring in greater detail to Figure 1, the shank 5 has an upwardlytapered and threaded portion 6 for engaging in a drill string and threedownwardly extending legs I. Upon these legs are mounted three cones 8arranged so that their apexes converge toward the center line of theshank. The shank 5 is so constructed as to allow minimum space betweenthe cutting teeth 9 and the shank. This is accomplished by extending theshank downward to form an enclosure between the three downwardlyextending legs. This extended flange portion M of the shank forms arounded concave central section at the lower end of the shank and willgreatly minimize the escape of fluid over the top of the cutting teethat this point. Fluid that does escape atthis point obviously does nocleaning. With the arrangement as described, most of the fluid will bedirected at the teeth and into the bottom of the hole being drilled.

In Figure 2 the cutting cones are formed with cutting teeth 9 arrangedin circumferential rows around the tapering periphery of the cone. Therows of teeth on the cone mounted most outwardly from the apex of thecone are on a different taper than those in adjacent rows. Each adjacentrow is offset longitudinally of the cone from each other adjacent row.The cutting cone 9 is mounted in the conventional way onto one ofthedownwardly extending legs 3.

Referring to Figure 3, the shank 5 of the bit has a centrally locatedmud channel 19. A circular baffle plate II with a centrally drilled holeI2 is mounted at the lower extremity of the mud channel within the bodyportion of the bit and having its periphery enclosed by the threedownwardly extending legs 3. At its lower end'the mud channel [0 isprovided with three mud discharge conduits [3. These conduits are 120apart around the mud channel and are positioned to correspond with eachof the three downwardly projecting legs. These conduits form a passagefor the mud or flushing fluid so as to direct the fluid around thebaflle plate H and onto the cutting teeth 9. It will be noted that thisarrangement causes the fluid to impinge upon the teeth from their baseends instead of directly against their faces.

In Figure 4 the baffle plate I I is located at the lower end of the mudchannel l0 and mounted with relation to the mud discharge conduits 13 soas to allow the flushing fluid from the mud channel I!) to pass aroundthis baffle plate and to be directed into the teeth 9 from their ends.

While a particular construction of the cutting bits and the downwardlyextending legs has been shown, it will be apparent that the invention isindependent of these features and may be used in any construction ofdrill bit in which washing of the cutting edges is desired.

What I claim is:

1. A roller cone rock bit comprising: a shank, downwardly depending legson said shank, an extended flange portion on said shank between saidlegs, a downwardly facing concave rounded central section on said shankbetween said legs, conically shaped cutter cones rotatably supportedfrom said legs, a circumferential row of teeth at the base of each cone,a circular central fluid channel extending axially downward through saidshank, means across the lower end of said channel substantially reducingthe diameter thereof; said concave section forming a close fit with theadjacent base end of said teeth, discharge conduits extending radiallyoutward from said channel and opening at said concave section at aposition of vertical alignment with and above the center line of saidcone and adjacent said base end of said teeth, said conduit including anabrupt bend intermediate its length whereby fluid passing through saidconduit is adapted to discharge out of said conduit over the base end ofsaid teeth and pass along the sides of consecutive teeth and parallel tothe bottom of said teeth for cooling and flushing purposes.

2. A roller cone rock bit comprising: a shank, an upper threaded portionon said shank, downwardly depending legs on said shank, an extendedflange portion on said shank between said legs, a downwardly facingconcave rounded central section on said shank between said legs,conically shaped cutter cones rotatably supported from said legs, acircumferential row of teeth at the base of each cone, a circularcentral fluid channel extending axially downward through said shank, abaffle plate across the lower end of said channel substantially reducingthe diameter thereof; said concave section forming a close fit with theadjacent base end of said teeth, discharge conduits extending radiallyoutward from said channel near said baflle plate and opening at saidconcave section at a position of vertical alignment with and above thecenter line of said cone and adjacent saidbase end of said teeth, saidconduit including an abrupt bend intermediate its length whereby fluidpassing through said conduit is adapted to discharge out of said conduitover the base end of said teeth and pass along the sides of consecutiveteeth simultaneously and parallel to the bottom of said teeth forcooling and flushing purposes, a portion of said fluid passing throughsaid reduced diameter and combining with said first mentioned fluidbelow said discharge opening.

References Cited in the file of this patent UNITEDSTATES PATENTS NumberName Date 1,263,802 Reed Apr. 23, 1918 1,641,261 Fletcher Sept. 6, 19271,656,471 Childs et a1 Jan. 17, 1928 1,762,570 Behnke June 10; 19301,784,476 Zublin et al Dec. 9, 1930 2,104,823 Sherman Jan. 11, 193-82,184,065 Zublin Dec. 19, 1939 2,293,603 Francis Aug. 18, 1942 2,320,137Kammerer May 25, 1943 2,325,745 Crum Aug. 3, 1943 2,334,359 StanclifiNov. 16. 1943

